There is a feature that I want in a To-do app that I am finding surprisingly hard to find. I would like a form of repeating due-date that does x amount of time since the last time it was done. That last part I am finding exceedingly difficult to find. Almost all apps I have found so far essentially pre-schedule all of the repeating reminder and ignore when you last did it. An example: Cleaning the house. I would like a reminder to do it every 2 weeks. However, sometimes, I might be gone or busy so I don't get to it until a week late. I want to then be reminded in 2 weeks, not 1 week because the task really doesn't help to do it sooner. The only app I have found so far that does this is Remember the Milk but the $25/year price tag to actually make it useful (push notification! and syncing more than once a day) is quite pricey. Does anyone know of any other apps that have this kind of reminder?